Knife grinder



Fell i8, 1969 M. L. HOCH ETAL KNIFE GRINDER Fil ed Oct. 7, 1966 INVENTORS Manfried L. Hoch m $1,. T 5 m h A T W; llriur k 1 FL. u r. PHI 1 u uu un Kw- I ll -n llllunlllll williillii I 4 Rona/d F. Zifko James D. Wilkins Ahy.

Feb. 18, 1969 M. L. HOCH ETAL 3,427,753

KNIFE GRINDER I Filed Oct. 7, 1966 Sheet 3 of FIG. 6

INVENTORS Manfr/ed L. Hoch gonaldpFwzlifko ames i ins Affy.

FIG. 7

United States Patent 12 Claims ABSTRACT OF THE DISCLOSURE A guide for a helical knife for sharpening against a grinding wheel, the guide comprising a bar of helical form conforming to the edge profile of the knife and 6p erative within the grooves of a pair of rollers spaced lengthwise of the bar, the bar being adapted to be positioned in a second set of guide rollers for positioning the cutting edge at a different angle to the grinder to obtain a second bevel.

The present invention relatesto a knife' grinder. The invention is particularly adapted for sharpening knives of kinds used in agricultural implements.

A broad object of the invention is to provide a grinder adapted for sharpening knives of different kinds and shapes.

A more specific object is to provide a grinder which includes a grinding fixture, or knife holder, which constitutes a small component of the entire machine specially designed for a particular kind of knife, and whereby a plurality of such fixtures or components can be provided for different kinds of knives, relatively inexpensively, and convenient in use whereby to readily accommodate knives of different kinds.

An additional object is to provide a knife grinder of the foregoing general character which is of extremely simple and inexpensive construction although unusually effective for the sharpening functions for which it is designed.

. A further object is to provide a knife grinder of the foregoing general character having a knife holder or fixture which can be placed in different positions in the sharpening operations, whereby to produce different angles of sharpening, or bevels, in the knife.

A more specific object is to provide a knife grinder of the character just referred to which includes a fixture or knife holder and a guide means therefor, wherein the knife is mounted in a fixed position in the fixture for the grinding operation, and the guide means accommodates the fixture or holder in eachof a pluralityof different positions without repositioning the knife in the fixture.

A further object is to provide a knife grinder of the foregoing general character which can be quickly put in use for the intended grinding operation, which is safe in operation, and in the use of which no unusual skill is required.

Other objects and advantages of the invention will appear from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a knife grinder made according to the present invention; I

FIG. 2 is a top view of the front portion of FIG. 1 but with the fixture or knife holder removed therefrom; FIG. 3 is an end view taken from the right of FIG. 2 but showing the knife holder in position;

FIG. 4 is an elevational view of a knife holder;

FIG. 5 is an end view taken from the right of FIG. 4;

FIG. 6 is an elevational view, similar to FIG. 4, but of a different form of knife holder; and

FIG. 7 is an endview taken from the right of FIG. 6.

Referring now in detail to the accompanying drawings attention is directed first to FIG. 1 showing a knife grinder made according to the present invention. The grinder indicated in its entirety at 10 includes three main parts, a bench grinder 12, a guide roller assembly 14 and a grinding fixture or knife holder 16. The bench grinder 12 may be of conventional constructoin and includes a grinding wheel 18 of suitable kind, having, for example, a beveled or conical grinding face 20 for providing a relatively restricted grinding surface for convenience in .applying the knife in the grinding operation. This beveled facealso appears in FIG. 2 which shows the wheel 18 mounted on a suitable shaft 22 arranged for driving by a suitable power means (not shown). The grinding wheel may be enclosed in a cabinet 24 having an opening or window 26 for exposing the grinding wheel and receiving the edge of the knife to be ground. The grinder 12 and guide roller assembly 14 are preferably mounted on a common support or bench 28 for establishing the direct relation therebetween as referred to again hereinbelow.

The guide roller assembly 14 includes a base 30 which may be a flat plate directly supported by the bench 28 and having slots 32 at its ends receiving nut-bolt means 34 which also extend through apertures 36 in the bench 28 for enabling adjustments of the assembly toward and from the grinding wheel 18 and releasably securing it in such adjusted positions. Secured to the base plate 30 and extending upwardly therefrom, are front and rear support elements or plates 38 and 40 in which are mounted parallel shaft 42 and 44 supporting pairs of grooved rollers 46 and 48, one of each pair being on each of the shafts, there thus being two rollers on each shaft. The front support element 38 is preferably higher than the rear support element 40, correspondingly supporting the shafts 42 and 44 inclined downwardly toward the grinder wheel. Also incorporated in the guide roller assembly 14 is an L-shaped safety lock 50 having one leg 52 mounted on a member 54 slidable in the front and rear support elements 38, 40 and another leg 56 extending over the top of the support element 40. The safety lock 50 is controlled by a manually operable means 58 which may be of any desired kind, including for example a spring 60 for securing the safety lock in locking position and enabling its release therefrom as referred to below. The safety lock includes a pilot pin 61 insertable in a hole in the rear support element 40 to prevent rotation of the safety lock and consequent interference with the traverse of the knife.

The fixture or knife holder 16 shown in FIGURE 1 is designed for holding or mounting a knife 62 of special shape, in this case of curved shape, as distinguished from a straight knife. This knife holder 16 is shown in FIG- URES 4 and 5, while a similar holder for holding a straight knife is shown in FIGURES 6 and 7, both holders being essentially the same, including the same elements of construction, but of different shape. The following detail description applies to the holder of FIGURES 4 and 5.

Referring now specifically to FIGURES l, 4 and 5 the knife holder 16 includes a bar 64, round in cross section, having handles 66 each of which may include a steel strap 68 secured to the bar and a hand grip 70 thereover. Preferably the steel strap extends below the bar as indicated at 72 for a safety feature to be referred to below.

A pair of mounting lugs 74 are secured to the bar 64, as by welding, in spaced relation therealong, each having a hole 76 adjacent at its extended end and an abutment stop 78 adjacent its inner end. The knife 62 is fitted flat to the lugs and secured thereto as by nut-bolt means 80, the abutment stops 78 being engaged by the back edge of the knife to aid in properly locating the knife.

Many knives, as in choppers and cutters, are of curved or helical shape and it becomes difficult to sharpen this type of knife in a device normally used for sharpening straight knives. The knife holder 66 of FIGURES 4 and 5 is shaped according to the helical shape of such knife, a different knife holder being provided for each size and shape of knife. In the present instance the bar 64 is curved complementarily to the helical shape of the knife, and the lugs 74 are mounted on the bar in mutually angularly offset relation following the helical shape of the knife. The arrangement is such that at every cross section through the knife mounted on the holder, the relation of the knife to the bar 64 is identical. The handles 66 themselves may also be relatively angularly displaced for convenience to the operator in manipulating the knife holder.

In using the device the operator places the bar 64 on the inner rollers 46 and rocks the holder to bring the cutting edge of the knife into engagement with the beveled surface of the grinding wheel. The roller assembly 14 is positioned so that a line passing through the two rollers 46 is essentially and operatively parallel with the beveled surface at the point of knife contact, modified from that exact relationship in the case of helical knives. The operator then grasps the handles 66 and reciprocates the holder over the rollers 46, keeping the cutting edge of the knife in grinding engagement with the wheel. The knife is stably supported, being provided a 3-point support, namely the two rollers and the engagement with the grinding wheel. As the knife holder is moved back and forth the knife continues to engage the grinding wheel in exactly the same angular relation at all positions of the knife, maintaining a constant bevel 82 or angle of sharpening on the knife. The helical contour of the holder 16 being the same as that of the knife, the desired constant angular relation between the blade and grinding wheel is maintained at all positions therealong.

The distance from the rollers 46 to the grinding wheel determines the angle of the bevel ground on the knife and this bevel may be as desired by repositioning the guide roller assembly 14 along the slot 32, to a limited extent, and for a greater adjustment the bolt-nut means 34 may be relocated in different holes 36.

The safety lock 50 is positioned so that the upper leg 56 engages over the bar 64 and this prevents the knife holder from being accidentally removed from the rollers, and prevents unsteady movement. The safety lock may be manually released for removing the knife holder and replacing it in sharpening position. The specific details of construction, and the manner of manipulating the safety lock may be as desired.

The knife holder shown in FIGS. 6 and 7, as stated above, is basically the same as that shown in FIGS. 4 and 5, except that the bar 64 is straight, the lugs 74, and the handles 66, are respectively in alignment.

In certain types of forage harvesters a second bevel is desired on the knife, this second bevel previously being formed by an auxiliary attachment to the grinding machine. The present device provides a simple arrangement for producing this secondary bevel, and quickly and easily so. After the primary sharpening operation, with the knife holder located in the rollers 46, and forming the primary bevel 82, the knife holder is removed from the rollers 46 and relocated on the rollers 48, changing the angle of the knife to the grinding wheel, producing a secondary bevel 84. The knife is manipulated back and forth in the same manner as described above, and as complete control is established in forming this secondary bevel as in sharpening the knife in the first instance.

There is another safety feature provided by the projections 72 on the handles, which prevent overrun of the knife holder, by engaging the rollers if the operator should accidentally attempt to move the holder too far.

The apparatus is of extremely simple nature and is readily and quickly adaptable to knives of different shapes.

The same grinder unit 12 and guide roller assembly 14 are utilized in the case of all of a variety of knives, and for different shapes of knives only the knife holder 16 need be changed. The apparatus as a whole does not need to be set up for different kinds of knives, the only operation being necessary is providing the different knife holders and securing the knives thereto. Additionally, the apparatus does not need to be set up as in the usual relatively complicated operations for producing the primary and secondary bevels, but the operator need only relocate the knife holder in the different sets of rollers 46, 48.

While we have herein disclosed a preferred form of the invention it will be understood that changes may be made therein within the spirit and scope of the appended claims.

We claim:

1. Apparatus for sharpening a knife, having a helical cutting profile comprising a driven grinder element, guide means including a pair of guide elements spaced along a line transverse to the face of the grinder element, a holder for the knife including a bar of helical shape conforming to the cutting edge profile and means for mounting the knife on the bar at a location on the knife removed from its cutting edge, the bar having guiding engagement with and detachably supported by said guide elements and movable thereon along said line, and the knife holder being rockable when on the guide elements for moving the cutting edge into and out of engagement with the grinder element.

2. The apparatus according to claim 1 wherein the guide elements are grooved rollers and the bar rests therein, and the knife holder is guidable about the axis of said bar.

3. The apparatus according to claim 1 wherein the grinder element includes a wheel rotatable on a horizontal axis and has a conical surface, and the guide elements are spaced along a line essentially and operatively parallel with an element of said conical surface and on opposite sides of that surface.

4. The apparatus according to claim 1 wherein a plurality of sets of guide elements are provided at different distances from the grinding element, and the knife holder is engageable selectively with the different sets, whereby the cutting edge of the knife engages the grinder element at different angles corresponding to the different sets of guide elements.

5. The apparatus according to claim 1 wherein the guide means is adjustable toward and from the grinder clement whereby to selectively provide different angles of bevels on the cutting edge of the knife.

6. The apparatus according to claim 1 wherein the knife holder is a separate component from the guide means, the guide elements face generally upwardly, and the knife holder is detachably supported on the guide elements.

7. The apparatus according to claim 6 wherein lock means is provided, releasable under manual control, for retaining the knife holder on the guide elements.

8. The apparatus according to claim 1 wherein the knife holder includes a longitudinal bar and handles at the ends thereof, the knife is mounted on the bar, and the bar is of such shape complementary to the knife that at all positions along the bar, sections through the knife and bar are identical.

'9. The apparatus according to claim 1 wherein the bar is provided with lugs spaced longitudinally therealong for detachably mounting the knife, and the lugs are mutually angul-arly offset corresponding to the helical progression of the knife.

10. The apparatus according to claim 9 wherein the knife holder includes handles at the end of the bar beyond the ends of the knife, and the handles are mutually offset angularly corresponding to the helical progression 0f t knife.

11. The apparatus according to claim 1 wherein the knife holder includes handles at the ends of the bar beyond the knife, and the knife holder is provided with projections adjacent to the handles serving as limit stops for engaging the guide elements to prevent overrun of th knife holder relative to the guide elements.

12. The apparatus according to claim 1 wherein the apparatus includes a common grinder unit including said grinder element, and a guide assembly unit including said guide elements, and a plurality of knife holder unit s separate and detached from the other units, the knife holder units being of respectively different shapes for mounting corresponding different shapes of knives, each knife holder unit including a longitudinal bar supportedly holders are reciprocal along the guide elements in the same manner.

References Cited UNITED STATES PATENTS LESTER M. SWINGLE, Primary Examiner.

D. G. KELLY, Assistant Examiner.

US. Cl. X.R.

engaging the guide elements whereby all of the knife 15 51 102 

